Galileo on the sizes and distances of the planets / Albert Van Helden.
Abstract:
During his university education, Galileo learned the traditional sizes and distances of the heavenly bodies. The telescope showed him, however, that the fixed stars and planets had much smaller apparent diameters than had been thought up to then. Although he repeatedly made this point in his works, he never supplied the learned world with a new scheme of planetary apparent diameters. This was first done by Martinus Hortensius in 1633. Galileo's ideas about planetary distances were entirely conventional. His solar system was, thus, the same size as Copernicus', but after the Sun the Earth was now by far the largest body in it
Annali dell'Istituto e Museo di storia della scienza di Firenze A. 7, fasc. 2 (1982), p. 65-86